Automatic blow-out preventor means



Se t. 21, 1965 c. B. COCHRAN ETAL AUTOMATIC BLOW-OUT PREVENTOR MEANS 6Sheets-Sheet 1 Filed March 21, 1963 CHUDL E I6 8. L Off/KAN JAMES D. M077- J. E. EDWARDS JR.

INVENTOR.

ATTORNEY P 1965 c. B. COCHRAN ETAL 3,207,221

AUTOMATIC BLOW-OUT PREVENTOR MEANS 6 Sheets-Sheet 2 Filed March 21, 19654 M m N 7/ Mr 5 x P k m imam": e a a ammm .IE 3 u H .E 7 a a p Aim lzzfi. V w .m 6% mm m IIILIE 9 4 4 J 2 Z n ATTORNE Y p 21, 1965 c. B.COCHRAN ETAL 3,207,221

AUTOMATIC BLOW-OUT PREVENTOR MEANS Filed March 21, 1963 6 Sheets-Sheet 3B.COCHRWV MES 0 ATTORNEY Sept. 21, 1965 C. B. COCHRAN ETAL AUTOMATICBLOW-OUT PREVENTOR MEANS 6 Sheets-Sheet 4 Filed March 21, 1963 J. E.EDWIODi JR.

4 INA? cl/wu/a/ flax/{RAN JAMES D. MOTT p 21, 1955 c. B. COCHRAN ETAL3,207,221

AUTOMATIC BLOW-OUT PREVENTOR MEANS 6 Sheets-Sheet 5 Filed March 21, 1963p 21, 1965 c. B. COCHRAN ETAL 3,207,221

AUTOMATIC BLOW-OUT PREVENTOR MEANS 6 Sheets-Sheet 6 Filed March 21, 1963N w a 52 M50 M 1 B m 0mm 5. L E 0 0 J a d" Pv w \v Z 1. m

wrmmw mm United States Patent 3,207,221 AUTOMATIC BLOW-OUT PREVENTORMEANS Chudleigh B. Cochran, James I). Mott, and Joseph E.

Edwards, Jr., Houston, Tex., assignors, by mesne assignments, to BrownOil Tools, Inc., Houston, Tex., a corporation of Texas Filed Mar. 21,1963, Ser. No. 266,960 9 Claims. (Cl. 166-85) This invention relates toautomatic blow-out preventors for well pipes and more particularly toautomatic stripper-type blow-out preventors.

In the operation of oil and gas wells, it is frequently necessary to runpipe strings, usually tubing strings, into and out of the well bores,while the well is under high fluid pressure. Various blow-out prevent-ormeans are conventionally employed to control the pressure while the pipeis being run. In one common system two or more conventional ram-typepreventors are installed in spaced-apart relation on the wellhead toconfine the pressure between the tubing and easing. At least twopreventors are necessary because the tubing string being run isordinarily made up of sections joined by collars larger in externaldiameter than the tubing sections. Since the collars cannot be passedthrough the rams while they are closed about the tubing, the rams mustbe worked alternately, releasing one to allow a collar to pass throughwhile the other is confining the pressure in the annulus between thetubing and the casing. This operation is timeconsuming and can behazardous because of the possibility that both preventors mayaccidentally be opened at the same time, resulting in a blow-out orother condition dangerous to the well personnel.

In another conventional system, stripper-type seals are employed. Inthis system, unlike the ram-type systems, the seals are not opened andclosed about the tubing, but are continuous flexible bodies, usuallyhaving lip-type flanges which maintain continuous sealing engagementabout the tubing by virtue of the well pressure exerted against thesealing flanges. In such systems, the seals are necessarily under thewell pressure at all times, and passage of enlargements on the tubing,such as the collars, is eifected by forcibly moving the collars throughthe strippers, the resiliency of the strippers being depended upon toyield sufiiciently to permit passage of the collars. However, suchstrippers necessarily have a quite short life due to the excessive wearoccasioned by the forcing of the tubing enlargements through thepressureloaded seal elements. In some cases, the destructive wear is sogreat that the strippers will not last out the running of a string ofpipe of even moderate length, requiring shut-down of the operation toreplace the strippers.

Accordingly, it is a primary object of this invention to provideblow-out preventor systems for use in running pipe strings which avoidthe difficulties and disadvantages of the more conventional systems suchas are enumerated above.

A principal object is to provide a blow-out preventor system employing apair of seal elements in combination with sensing means responsive toenlargements on the tubing string being run in a well and cooperatingwith fluid-pressure-actuated operating means to automatically actuatethe seal elements alternately to confine the annulus pressure betweenthe casing and tubing, while contemporaneously automatically equalizingthe pressure across the non-actuated seal elements in the advance ofpassage therethrough of the enlargement.

Another object is to provide a blow-out preventor sys-' tem of thecharacter described wherein the seal elements may be either ram-type orstripper-type, and wherein the operating means is hydraulicallyactuated.

In accordance with one embodiment of this invention, a structure isprovided which includes a pair of longitudinally spaced stripperelements comprising resilient seal members adapted to sealingly engage atubing string or other pipe which is being run into a well and to sealthereabout when subjected to the annulus pressure between the pipestring being run and the well casing. Associated with the strippers aresensing elements which are responsive to the passage of enlargements onthe pipe or tubing string and which are operatively associated withoperating means actuated by fluid pressure to alternately actuate one ofthe stripper elements to confine the fluid pressure while equalizing thepressure across the other stripper element in advance of the passage ofthe enlargement through the stripper element. The alternate actuation ofthe stripper elements is efiected automatically by means of the sensingelements so that no manual manipulations are required to make sure thatan enlargement on the pipe or tubing string being run will not be causedto pass through a stripper element which is under pressure. At the sametime, the other of the stripper elements will be under pressuresufficient to maintain the necessary seal between the tubing string andthe casing.

In another embodiment in accordance with this invention, the sealelements are of the conventional ram-type which are automaticallyactuated in the same manner and by the same enlargement-sensing andactuating elements as are used for the stripper-type embodiment.

In yet another embodiment a somewhat modified hydraulic device isemployed for operating the seal elements in response to actuation by theenlargement-sensing elements.

Other and more specific objects and advantages of this invention willbecome more readily apparent from the following detailed descriptionwhen read in conjunction with the accompanying drawing which illustratesa useful embodiment in accordance with this invention.

In the drawing:

FIG. 1 is a view partly in section and partly diagrammatic illustratinga stripper blow-out preventor system in accordance with this invention;

FIGS. 2 and 3 are generally diagrammatic views illustrating successivestages in the operation of the device while a tubing string is being runinto a well;

FIGS. 4 and 5 are diagrammatic views similar to FIGS. 2 and 3illustrating the positions of the parts when a tubing string is beingpulled from a well;

FIG. 6 is a cross-sectional view taken generally along line 66 of FIG.1;

FIG. 7 is a cross-sectional view along line 7--7 of FIG. 1;

FIG. 8 is a perspective view of one of the control elements employed inthe system;

FIGS. 9 and 10 are generally diagrammatic views generally similar toFIGS. 2 and 3 but substituting ram-type seal elements for thestripper-type elements;

FIG. 11 is a cross-sectional view taken generally along line 1111 ofFIG. 10; and

FIGS. 12 and 13 are views generally similar to FIGS. 2

and 3, but illustrating a modified form of hydraulic actuating systemfor the seal elements.

Referring first to FIGS. 1 to 8 of the drawing, the blowout preventorstructure comprises a generally tubular housing, designated generally bythe letter H, adapted to be mounted on a wellhead fitting P, which maybe of any suitable type permitting the preventor housing H to besuitably supported in coaxial alignment with the bore of a well (notshown) but which, it will be understood, will be lined with the usualwell casing (not shown). The housing structure is designed to receive astring of pipe P which may be run into, or pulled from, the well throughthe bore of housing H.

Pipe P, which may be a string of well tubing, comprises a plurality ofpipe sections connected by collars C which form longitudinally spacedexternal enlargements about the pipe string.

Housing H is made up of a plurality of coaxial end-toend connected,generally tubular members which include upper and lower stripper sealunits S and S respectively, an upper enlargement-sensing unit Econnected to the upper end of upper stripper seal unit S and a lowersensing unit E connected between the stripper units.

Stripper units S and S are substantially identical in construction, eachcomprising a metallic tubular body 10 and a tubular sealing element 11concentrically mounted in the bore of body 10. Sealing element 11 isconstructed of a generally conventional flexible resilient compositionand has an inwardly projecting annular sealing portion 12 adapted tonormally have slidable sealing contact with the exterior of pipe P. Theends of sealing element 11 are secured to metal upper and lower endrings 13 and 14, respectively. Upper end ring 13 has an externaldownwardly facing shoulder 15 engageable on an internal upwardly facingshoulder 16 in the bore of body 10. Lower end ring 14 seats against anupwardly facing internal shoulder 17 in body 10. A lock pin 18 isscrewed through the wall of body 10 into a recess 19 in the lower endring. The shouldered engagement between upper end ring 13 and body 10and the cooperation between lower end ring 14, shoulder 17 and lock pin18 serve to lock the end rings to body 10, holding them stationary whilepermitting seal elements 11 to radially expand and contract, as willappear hereinafter. The inner wall of body 10 opposite sealing element11 is recessed to provide the annular chamber 20. One or more radialopenings 21 are provided through lower end ring 14 to provide fluidpressure communication between chamber and the annular space A definedbetween housing H and pipe P. It will be understood that annular space Ais in communication with the well annulus (not shown), that is, theannular space between pipe P and the wall of the well into or out ofwhich the pipe is being run.

The lower end of body 10 of lower stripper unit S is provided with athreaded pin 22 by means of which housing H is threadedly secured towellhead fitting F.

Upper and lower enlargement-sensing units E and E are also substantiallyidentical in construction. Each includes a mounting collar 25 whichforms a part of housing H and also functions to support the operativeelements of the sensing unit. The upper mounting collar connects a guidenipple 26, which forms the uppermost element of housing H, in axiallyspaced relation to the upper end of body 10 of the upper stripper unit,thereby providing the annular space 27 therebetween.

Lower mounting collar 25 connects bodies 10 of the upper and lowerstripper units in axially spaced relation to provide the annular space28 therebetween.

The operative elements of the sensing units include a plurality ofcontact pads 30 mounted for limited radial movement in spaces 27 and 28.The contact pads are conveniently constructed as segments of a ring(FIG. 6) arranged to surround pipe P and may be formed with forwardlyprojecting portions 31 on their inner surfaces to provide the pipecontacting points. Any desired number of pads 30 may be employed. Threeare shown in the illustrative embodiment. The top and bottom walls ofspaces 27 and 28 are provided with opposed keeper lips 32 and 33,respectively, which are adapted to cooperate with oppositely extendingflanges 34-34 at the rearward edges of the pads to confine the padswithin spaces 27 and 28 while permitting limited radial movement of thepads sufficient to project portions 31 into contact with pipe P.

Each of the pads 30 is urged outwardly of spaces 27 and 28 toward pipe Pby identical structures, each of which includes a hollow plunger 35which extends radially through the mounting collar and is slidabletherein. Plunger 35 has its inner end received in a socket 36 in theouter surface of pad 30 and its outer end enclosed by a cylinder 37which is screwed into the exterior of the mounting collar. The outer endof cylinder 37 is closed by a cap 38 having a socket 39 to slidablyreceive the outer end of plunger 35. A coil spring 40 is mounted insocket 39 in compression between the end of the plunger and the bottomof the socket 30 toward pipe P.

Plunger 35 carries a sealed piston 41 slidable in cylinder 37 with theplunger and defining a pressure chamber 42 between the piston and cap38. Pressure chamber 42 is adapted to contain a body of a suitablepressure fluid. A conduit 43 provides pressure fluid communicationbetween chamber 42 and an annular pressure fluid reservoir 44 formedwithin the body of mounting collar 25. As the pressure fluid systemwhich includes plunger 35 is a closed system, one of the severalconduits 43 may be connected to a small accumulator 45 to accommodateexcessive displacement of fluid in the pressure fluid system duringoperation of the device. A pipe 46 leads from conduit 43 of the uppersensing unit E to one of the inlet ports 48 of a four-way valve 47, ofgenerally conventional rotary construction, having a ported plug 470. Apipe 46a leads from conduit 43 of lower sensing unit E to another inletport 48a of valve 47.

A conduit 49 leads from one of the discharge ports 50 of valve 47 to oneend of control valve, designated generally by the letter V, and a secondconduit 51 leads from the other discharge port 5011 of valve 47 to theopposite end of control valve V. In one .position of plug 47a (FIGS. 1,2 and 3) conduits 46 and 46a are placed in communication with conduits49 and 51, respectively. In a second position of plug 47a (FIGS. 4 and5), conduits 46 and 4611 are put in communication with conduits 51 and49, respectively.

Control valve V constitutes a portion of a second closed fluid pressuresystem, referred to herein as the actuating system, which is adapted toactuate strippers 11 alternately in response to actuating signalsreceived from the sensing units. The actuating system controls apressure equalizing conduit 55, the opposite ends of which communicatethrough ports 56 in bodies 10 with pressure chambers 20 of the stripperunits S and S A generally conventional three-way rotary valve 57 (shownin perspective in FIG. 8) is mounted in conduit 55 and includes :acasing 58 having three ports 58a, 58b and 580, two of which, 58a and581:, are in communication with branches of conduit 55. Port 580communicates with a bleed conduit 59. A plug member 60 is rotatablymounted in casing 58 and is adapted to oscillate between two positionsfor selectively placing chambers 20-20 in communication with each otheror only upper chamber 20 with bleed conduit 59. Plug member 60 is drivenby means of a shaft 61 connected to a vane motor 62 which is mounted ina casing 63 and is caused to oscillate by fluid pressure directed intocasing 63 through one or the other of a pair of inlet ports 64 and 65which are in communication with pressure fluid conduits 66 and 67,respectively, which lead from control valve V.

Control valve V is a generally conventional multi-port spool-type valvecomprising a tubular casing 70 and a spool-type valve member 71slid-able axially in the case 5 ing. Valve member 71 is formed with apair of enlarge ments 7272 at its opposite ends and a third enlargement73 intermediate the end enlargements, the several enlargements havingslidable sealing engagement with the wall of casing 70. The threeenlargements define between them a pair of annular passageways 74 and 75which communicate, respectively, with outlet ports 76 and 77 at allpositions of the spool member. Outlet ports 76 and 77 communicate withpressure fluid conduits 66 and 67, respectively. A pair oflongitudinally spaced vent ports 78 and 79 are provided through the wallof casing 70 and are longitudinally spaced so that only one of them willbe in communication with one of the passageways 74 and 75 at anyposition of valve member 71. Thus, when valve member 71 is in theposition shown in FIGS. 1 and 2, passageway 75 will be in communicationwith vent port 79, while passageway 74 will be cut off from vent port 78by an end enlargement 72. When valve member 71 has been shifted to theopposite end of casing 70 (FIG. 3), passageway 74 will be incommunication with vent port 78 while passageway 75 will be cut off fromcommunication with vent port 79. Vent ports 78 and 79 are connected to acommon header 80 which leads to a pressure fluid accumulator tank 81.

An inlet port 82 communicates with valve casing 70 at substantially themid-point thereof, being located to communicate with one or the other ofpassageways 74 and 75, depending upon the position of valve member 71.Inlet port 82 is connected to a pipe 83 which leads to tank 81 and has apump 84 positioned therein to deliver fluid under pressure to valve Vthrough inlet port 82.

Mounted on the opposite ends of valve casing 70 are pressure cylinders85 and 86 in which are disposed pistons 87 and 88, respectively, mountedon rods 89 and 90, respectively, which slidably project through the endwalls of casing 70 into engagement with the opposite ends of valvemember 71. Pistons 89 and 90 are biased outwardly with respect to endsof casing 70 by means of the springs 91. Cylinder 85 is in communicationwith conduit 49 and cylinder 86 with conduit 51, the cylinders therebyforming part of the closed pressure systems which include sensingelements E and E The blow-out preventor is operated in the followingmanner: As seen in FIG. 1, pipe string P is in process of being run intoa well through the blow-out preventor structure herein described. At thestage shown, collar has moved opposite pads 30 of the upper sensingelement E and has forced the pads rearwardly against the pressure ofsprings 40, thereby moving pistons 41 rearwardly and displacing pressurefluid from chambers 42 through conduits 43 into reservoir 44. Some ofthe displaced fluid will be forced through conduit 46 and throughmultiport valve 47 via ports 48 and 50 into conduit 49 which willdeliver the displaced pressure fluid into cylinder 85. The pressurefluid will act on piston 87, driving valve member 71 to the positionshown in FIG. 1. This will place pressure fluid supply conduit 83 intocommunication with passageway 74 while passageway 75 is placed incommunication with vent port 79. The pressure fluid will flow throughpassage 74 and thence through ports 76 and conduit 66 against one sideof vane motor 62, which will rotate plug 60 of valve 57 to the positionshown in FIG. 1. The fluid in the other side of the vane motor willdrain back through conduit 67, valve passageway 75 and manifold 80 tothe storage tank 81. This movement of valve 57, as shown, will permitpressure chamber 20 of upper stripper unit to be vented through conduit55 to bleed pipe 59 and will equalize the pressure in chamber 20 ofupper stripper unit S with the atmosphere. At the same time, with valveplug 60 in the position shown in FIG. 1, conduit 55 will be cut ofiffrom pressure chamber 20 of the lower stripper unit S which will then beunder the pressure of the well fluid in annulus A. As a result, stripperelement 11 of the lower stripper unit 8,, will be actuated to form afluid-tight seal about pipe P, thereby confining the annulus pressure atthis point while the upper stripper unit is relieved of the wellpressure through bleed pipe 59. As the pipe string moves downwardly,therefore, stripper element 11 of upper stripper unit S will relax,allowing collar C to pass through easily and without damage to thestripper element. FIG. 2 illustrates, diagrammatically, the positions ofthe several parts :at the stage of operations just described, at whichcollar C has passed the upper sensing unit and is passing through theupper stripper unit S As the pipe string continues to move down andcollar C passes the sensing pads of lower sensing unit E the latter isactivated to displace pressure fluid through conduits 43, 46a and 51into cylinder 86, moving piston 88 in a direction to drive valve member71 to the opposite end of casing 70, as seen in FIG. 3. When thisoccurs, passageway 75 will be placed into communication with pressurefluid from conduit 83 while passageway 74 is connected to vent passage'78. The pressure fluid will be transmitted through conduit 67 to theother side of vane motor 62, rotating plug 60 of valve 57 to theposition shown in FIG. 3, at which pressure chambers 20 of both stripperunits S and S will be placed into communication with each other,applying annulus pressure to upper stripper unit S and thereby actuatingthe sealing element of the upper stripper unit to close the annulusbetween pipe P and housing H, while passing through port 21 andequalizing the pressure across the lower stripper unit. This willrelieve the latter from the pressure load so that collar C may passthrough the lower stripper element 11 without exerting any serious dragor destructive force thereon. When the next collar reaches sensing unitE the operations will be repeated, that is, lower stripper S will beactuated to seal the well annulus about pipe P, while the pressureacross the upper stripper unit is equalized with the atmosphere, freeingit for ready passage of the next collar.

To pull the string of pipe from the well under pressure, the only changerequired is to rotate plug 47a of valve 47 to the position shown inFIGS. 4 and 5. In this position, conduit 46a will be placed intocommunication with conduit 49 and conduit 51 will be placed intocommunication with conduit 46, and all other connections will be exactlyas shown in FIGS. 1 to 3 and as previously described.

It will be assumed that collar C in FIG. 4 will have passed throughlower stripper unit S while the latter is under equalized pressure, asthis was the case in order for the collar to have moved downwardlythrough the stripper initially. As collar C moves upwardly opposite thepads of lower sensing unit E the latter will be actuated to displacepressure fluid through conduits 46a and 49 by way of valve plug 47a tocylinder 85, moving valve member 71 again to the position shown in FIG.4, which is exactly the same position as in FIGS 1. and 2. In thisposition, the pressure fluid from tank 81 will be delivered from conduit66 to vane motor 62, moving plug 60 to a position placing conduit 55 incommunication with bleed pipe 59, while cutting off communication tolower pressure chamber 20. Whereupon, the lower stripper unit S will beactuated by the annulus pressure to seal otT the well annulus while thepressure across upper stripper unit S will be equalized with theatmosphere through bleed conduit 59. Thereupon, when the pipe string ispulled upwardly, collar C will pass through the upper stripper element,which will have been unloaded of its pressure and upon-contacting thepads of upper sensing unit E as shown in FIG. 5, the pressure fluiddisplaced thereby through conduit 46 and conduit 51 via plug 47a ofvalve 47 will enter cylinder 86 and act on piston 88, moving valvemember 71 to the opposite position, shown in FIG. 5. Thereupon, pressurefluid from conduit 83 will flow through passageway 75 via conduit 67 tothe other side of the vane motor 62, moving plug 60 of valve 57 to theposition shown in FIG. 5, whereby the annulus pressure will becommunicated to the upper stripper unit S to actuate the stripperelement therein to seal off the annulus between pipe P and housing H,while equalizing the pressure across the lower stripper unit S inadvance of the entry therein of the next collar on the pipe string.These operations will be repeated as each collar approaches each of thestripper units until the string of pipe has been withdrawn from thewell.

In the foregoing description, the sensing units and the control elementsare described as being actuated by means of a hydraulic pressure fluid.It will be readily evident, however, that one or both the sensing unitsand the control unit may be actuated with pneumatic pressure fluid.While this will require the use of pneumatic systems involving pilotvalves and other conventional pneumatic equipment, the changes necessaryto convert to use of a pneumatic fluid will be readily evident to thoseskilled in the art, and will involve no significant modifications of theinvention herein disclosed.

It will be evident that in accordance with this invention a novel systemis provided whereby two strippertype units may be employed as theblow-out preventors and are automatically operated to permit passage ofenlargements on a pipe string when the pressure load is removed from oneof the stripper units, the other being simultaneously actuated to sealoff the annulus between the pipe string being run through the Well boreand the wall of the well bore.

FIGS. 9, and 11 illustrate a modification in which conventional ram-typesealing units, designated generally by the letters R and R aresubstituted for the corresponding stripper-type units of the previouslydescribed embodiment. Each of the ram-type blow-out preventor units Rand R includes a casing 92 adapted for mounting transversely in housingH. A pair of opposed rams 93 are slidably mounted in casing 92 to sealoff the annular space between pipe string P and housing H when the ramsare advanced to engage about the pipe string. The rams are operated bymeans of pistons 94 secured to the outer ends of the rams and working incylinders 95 formed in the outer ends of casing 92. Springs 96 normallybias the rams to the retracted position. Pressure fluid is supplied tocylinders 95 through a header 97 which, in unit R communicates withconduit 66, and in the case of unit R with conduit 67.

Since rams R and R constitute positive-type seals, the pressureequalizing connections comprising ports 56 and conduit 55 may beeliminated, together with rotary valve 57 and vane motor 62. Instead,conduits 66 and 67 are connected directly, as noted, to headers 97 oframs R and R respectively. I

With this arrangement, it 'will be seen that when upper sensing unit Eis actuated by an enlargement, valve V will be actuated in exactly thesame manner as previously described to deliver pressure fluid throughconduit 67 to lower ram unit R closing the latter about pipe P. Thismovement places upper ram unit R in communication through pipe 66 withreturn pipe 80 leading to the accumulator tank 81. The biasing spring 97will cause retraction of rams 93 of ram unit R and thereby opens theseal to the passage of the enlargement.

When the enlargement engages the sensing element of sensing unit E valueV will be actuated, as previously described, to place conduit 66 inpressure communication with the pressure fluid supply, closing upper ramunit R about pipe P above the enlargement. At the same time, thepressure on the rams of ram unit R will be relieved, allowing the latterto open for subsequent passage of the enlargement.

In pulling pipe, it will only be necessary to reverse valve 47, aspreviously described, the operation being otherwise exactly just asdescribed.

FIGS. 12 and 13 illustrate still another modification, and in thismodification, stripper units 8;, and S corresponding to stripper units Sand S respectively, are employed. The enlargement-sensing units E and Eare identical to those previously described. Pressure equalizing conduit55 connecting ports 56 through valve 57 .are employed in this embodimentexactly the same as in the first described embodiment. The vane motor 62is likewise employed for operating valve 57, as is multiport valve 47.However, instead of the external source of pressure fluid, such as tank81 and pump 84, and the multiport valve corresponding to valve V of thepreviously described embodiment, there is substituted a dual closedhydraulic system arrangement for operating vane motor 62. In thisembodiment, conduit 46, which leads from upper sensing unit E connectsto port 48 of valve 47 and thence via ports 50 to one end of a cylinder100, the other end of which is connected, by means of a conduit 101, toone side of vane motor 62. Conduit 46a is similarly connected to port48a of valve 47 .and thence via port 50a to conduit 51, which leads toone end of a second identical cylinder 100, the other end of which isconnected by a conduit 101 to the other side of vane motor 62. Eachcylinder is divided intermediate its ends by a partition 102 having acentral opening adapted to slidably receive a piston rod 103. The lattercarries an upper piston 104 reciprocable in the portion of cylinder 100on one side of partition 102, and a lower piston 105 reciprocable in theportion of cylinder 100 on the opposite side of partition 102. In eachcylinder the upper piston 104 is biased away from partition 102 by meansof a coil spring 106. The portion of cylinders 100 between lower pistons105 and conduit 101 contain bodies of hydraulic fluid 107 which areadapted to flow back and forth through conduits 101 between the relatedsides of vane motor 62 and the communicating portions of the relatedcylinders 100. Thus, two closed hydraulic systems are provided, eachincluding one side of vane motor 62 and the connected portion of therelated cylinder 100. It will be seen that when one of the pistons ismoved in the direction to compress the body of fluid 107, vane motor 62will swing in one direction, while the body of fluid 107 in the otherside of the vane motor will be forced back into the other cylinder 100,moving thepistons therein to the retracted position. When the pressureforces are reversed, the vane motor is swung in the opposite direction.

In operation: When upper sensing unit E is actuated by passage of acollar C, fluid pressure will be exerted through conduit 46 and ports 48and 50 in valve 47, and thence through conduit 49 against piston 104 inthe righthand one of cylinders 100. The piston will be forced downwardly(as viewed in the drawing), forcing the body of hydraulic fluid 107therein to act upon the side of vane motor 62 which will move plug 60 invalve 57 to the position shown in FIG. 12, in which lower seal unit 8.;will be held under pressure, sealing off about pipe P. The annular spacebetween the sealing units will be relieved through bleed pipe 59,thereby equalizing the pressure across the seal unit S As collar Cengages lower sensing unit E after passing through upper seal unit S thepiston in the left hand one of the cylinders 100 will be forceddownwardly, causing vane motor 62 to swing in the opposite direction andmoving valve 57 to the position shown in FIG. 13, wherein pressure isequalized across lower seal unit S while the annulus pressure istransmitted between the seal units to actuate the upper seal unit S toseal about pipe P'af ter collar C has passed therethrough.

As in the previously described embodiments, when the pipe 1 s beingpulled from the well the only change necessary 1n the structure shown inFIGS. 12 and 13, is to change the position of valve 47 to connect pipe49 to pipe 46a and conduit 46.

From the foregoing it will be seen that in each embodiment when runningpipe into the well, the second or lower of the two sealing units isactuated first to seal off about the pipe and equalize the pressureacross the first or 9 upper sealing unit. The first or upper sealingunit is actuated second in order to seal off about the pipe after theenlargement has passed it and thereby equalize the pressure across thesecond or lower of the two sealing units.

When pulling pipe from the well, positions of the seal units in order oftheir actuation is reversed. The upper seal unit becomes the second inorder of passage by the enlargement but is actuated first, while thelower seal unit becomes the first in order of passage by the enlargementbut is actuated second.

It will be evident, therefore, that the means employed to actuate theseal elements are arranged to successively actuate the seal elements ininverse order with respect to the direction of movement of theenlargement whereby to automatically equalize the pressure across eachseal element as it is approached by the enlargement.

It will be understood that numerous changes and alterations may be madein the details of the illustrative embodiment within the scope of theappended claims but without departing from the spirit of this invention.

What we claim and desire to secure by Letters Patent is:

1. Automatic blow-out preventor means for use when running pipe stringsinto and out of a well under pressure, comprising a tubular housingmountable on a well head fitting and through which a pipe string ispassed, spaced apart upper and lower contractible and expandible sealelements mounted in the housing actuatable to seal off the annular spacebetween the housing and the pipe string, an enlargement-sensing meansmounted in the housing adjacent each of the respective seal elementsincluding fluid pressure signal-transmitting means operable to providesignals indicating the approach of an enlargement on the pipe stringsuccessively toward the respective seal elements, fluidpressure-operated means operably connected to said signal-transmittingmeans actuatable in response to said signals and arranged tosuccessively actuate said seal elements in inverse order with respect tothe direction of movement of said enlargement, whereby to automaticallycontract each seal element as it is approached by said enlargement.

2. Automatic blow-out preventor means according to claim 1, wherein saidseal elements comprise radially movable segmental rams.

3. Automatic blow-out preventor means according to claim 1, wherein saidseal elements comprise annular resilient stripper-type units.

4. Automatic blow-out preventor means according to claim 1 wherein saidenlargement-sensing means comprises contactor elements radially movablymounted in said housing, means resiliently biasing said contactor meansinto maintained slidable engagement with the exterior of said pipestring whereby passage of an enlargement will efiect retractive movementof said contactor elements.

5. Automatic stripper-type blow-out preventor means for use when runningpipe strings into and out of a Well under pressure, comprising, atubular stripper housing mountable on a well head fitting and throughwhich a pipe string is passed, spaced apart upper and lower annularresilient stripper seal elements mounted in the housing for engagementabout the pipe string and actuatable by well pressure to seal off theannular space between the pipe string and the housing, conduit meansproviding well pressure communication between a point in said housingbelow the lower seal element and a point in said housing between saidseal elements, multi-port valve means in said conduit means movablebetween a first position opening communication between said points and asecond position closing ofl said communication while communicating onlysaid point between said seal elements with the atmosphere, anenlargement-sensing means mounted in the housing at a point adjacenteach of the respective seal elements operable to provide signalsindicating the approach of an 10 enlargement on the pipe stringsuccessively toward the respective seal elements, fluid pressuresignal-transmitting means operable by said sensing means, fluidpressureoperated means actuatable in response to said signals tosuccessively move said valve means to said first and second positions,whereby to successively equalize the pressure across each seal elementas it is approached by said enlargement while simultaneously directingwell pressure to the other seal element to actuate the latter to sealoff the annular space between the pipe string and the housing.

6. Automatic stripper-type blow-out preventor means according to claim 5wherein said enlargement-sensing means comprises contactor elementsradially movably mounted in said housing, means resiliently biasing saidcontactor means into maintained slidable engagement with the exterior ofsaid pipe string whereby passage of an enlargement on the pipe stringwill efiect retractive move ment of said contactor elements.

7. Automatic stripper-type blow-out preventor means according to claim 5wherein said enlargement-sensing means comprises contactor elementsradially movably mounted in said housing, means resiliently biasing saidcontactor means into maintained slidable engagement with the exterior ofsaid pipe string whereby passage of an enlargement on the pipe stringwill effect retractive movement of said contactor elements, and whereinsaid signaltransmitting means is actuatable by said retractive movementto transmit said signals for moving said valve means.

8. Automatic stripper-type blow-out preventor means for use when runningpipe strings into and out of a well under pressure, comprising, atubular stripper housing mountable on a well head fitting and throughwhich a pipe string is passed, spaced apart upper and lower annularresilient stripper seal elements mounted in the housing for engagementabout the pipe string and actuatable by well pressure to seal off theannular space between the pipe string and the housing, conduit meansproviding well pressure communication between a point in said housingbelow the lower seal element and a point in said housing between saidseal elements, multi-port valve means in said conduit means movablebetween a first position opening communication between said points and asecond position closing off said communication while communicating onlysaid point between said seal elements with the atmosphere, anenlargement-sensing means mounted in the housing at a point adjacenteach of the respective seal elements operable to provide signalsindicating the approach of an enlargement on the pipe stringsuccessively toward the respective seal elements, fluid pressuresignal-transmitting means operable by said sensing means, fluid pressureop erated means actuatable in response to said signals from saidtransmitting means to successively move said valve means to said firstand second positions, whereby to successively equalize the pressureacross each seal element as it is approached by said enlargement whilesimultaneously directing well pressure to the other seal element toactuate the latter to seal off the annular space between the pipe stringand the housing.

9. Automatic blow-out preventor means for use when running pipe stringsinto and out of a well under pressure, comprising, a tubular housingmountable on a wellhead fitting and through which a pipe string ispassed, spaced apart upper and lower fluid pressure-operated sealelements mounted in the housing for radial movement into and out ofengagement about the pipe string to seal 01f the annular space betweenthe pipe string and the housing, conduit means providing fluid pressurecommunication to said seal elements, multi-port valve means in saidconduit means movable between positions for selectively directingpressure fluid to one or the other of said seal elements, anenlargement-sensing means mounted in the housing at a point adjacenteach of the respective seal elements including fluid pressuresignal-transmitting means operable to provide signals indicating theapproach of an enlargement on the pipe string successively toward therespective seal elements, said signals being operable to move said valvemeans to positions to direct operating pressure fluid successively toeach of said seal elements, whereby to successively equalize thepressure across each seal element as it is approached by saidenlargement while simultaneously directing fluid pressure to the otherseal element to actuate the latter to seal off the annular space betweenthe pipe string and the housing.

References Cited by the Examiner UNITED STATES PATENTS Rasmussen et al16685 King et al 25 l1 Rasmussen 166-85 X Abercrombie 251-1 Boynton16686 X 10 CHARLES E. OCONNELL, Primary Examiner.

1. AUTOMATIC BLOW-OUT PREVENTOR MEANS FOR USE WHEN RUNNING PIPE STRINGSINTO AND OUT OF A WELL UNDER PRESSURE, COMPRISING A TUBULAR HOUSINGMOUNTABLE ON A WALL HEAD FITTING AND THROUGH WHICH A PIPE STRING ISPASSED, SPACED APART UPPER AND LOWER CONTRACTIBLE AND EXPANDIBLE SEALELEMENTS MOUNTED IN THE HOUSING ACTUATABLE TO SEAL OFF THE ANNULAR SPACEBETWEEN THE HOUSING AND THE PIPE STRING, AN ENLARGEMENT-SENSING MEANSMOUNTED IN THE HOUSING ADJACENT EACH OF THE RESPECTIVE SEAL ELEMENTSINCLUDING FLUID PRESSURE SIGNAL-TRANSMITTING MEANS OPERABLE TO PROVIDESIGNALS INDICATING THE APPROACH OF AN ENLARGEMENT ON THE PIPE STRINGSUCCESSIVELY TOWARD THE RESPECTIVE SEAL ELEMENTS, FLUIDPRESSURE-OPERATED MEANS OPERABLY CONNECTED TO SAID SIGNAL-TRANSMITTINMGMEANS ACTUATABLE IN RESPONSE TO SAID SIGNALS AND ARRANGED TOSUCCESSIVELY ACTUATED SAID SEAL ELEMENTS IN INVERSE ORDER WITH RESPECTTO THE DIRECTION OF MOVEMENT OF SAID ENLARGEMENT, WHEREBY TOAUTOMATICALLY CONTRACT EACH SEAL ELEMENT AS IT IS APPROACHED BY SAIDENLARGEMENT.